Mexican “Transplants” for the Garden Landscape

by Bobby J. Ward

Those of us who grow plants often give little thought to their origins and the winding journeys they may have taken to reach our gardens. Many of the annuals and perennials we grow result from the efforts of plant hunters‐those often intrepid adventurers whose labors provide us with plant riches. The last decade has witnessed an infusion of new plants into the nursery industry from outside the United States, and the South has not been left out of this burgeoning green plenty.

An important contributor of garden plants is our neighbor Mexico, which has a wide range of habitats in addition to its familiar high deserts. Southerners have long recognized and grown sunflowers, marigolds, dahlias, rain lilies, and zinnias‐‐all garden stalwarts that originated in Mexico. There are, however, many under-used plants that can add variety to our landscapes and bring the charming piquancy of Mexico to our personal gardens.

Although I did not know its name, one of the first “foreign” plants I noticed while watching television westerns as a child was the agave. Known as century plant or maguey, its tall flowering spikes represent one stereotypical image of Mexico’s picturesque landscape. Agaves belong to a group of monocots sometimes referred to as “woody lilies,” whose members include the well-known Southern native yucca or bear grass. Their leaves are borne in a rosette, fleshy and stiff, and are often armed with sharp teeth or piercing spines. Many forms are easily hardy in USDA Zone 7 (down to zero degree F). Agave scabra has rough-textured foliage, silver-gray, on a plant that may grow up to three feet tall and three feet wide. Agave striata has smaller, outward-stretching, pencil-like leaves and tolerates light shade to full sun. Plant agaves in very well-drained soils in full sun. Many species easily adapt to pot culture and over-winter quite well indoors.

There are other agave-like plants to consider for adding distinctiveness and variety to your garden landscape, including dasylirons and manfredas. Dasylirion wheeleri, the blue sotol, grows to about three feet tall. It is an explosion of fine-textured leaves that are blue-green and have small spines along their sides. Its small white flowers are arranged tightly on slender stalks. Though hardy in Zones 7 to 10, it needs to be keep relatively dry in the winter, and it will take full sun. Manfreda, also known as deciduous agave, is a stemless dry garden Mexican native. It is closely related to the spicy-fragrant tuberose, a well-known southern favorite, and to Manfreda virginica, a native of the upper South. Manfreda maculosa has a basal rosette of freckled foliage requiring full sun and good drainage. The foliage of Manfreda undulata is distinctive with undulating or wavy edges. This plant produces a late spring flowering stalk that may be up to three feet tall.

Another Mexican native, nolina, has drooping, grass-like evergreen leaves. It will grow in dry soil where there is plenty of sun. Its blue foliage is stunning. You should not overlook the Mexican yuccas. Yucca restart, the blue tree yucca, is cold hardy to zero degrees (Zone 7). Its blue-gray leaves have a cream-colored edge. This elegant plant likes full sun and dry soil. Unlike some of the other agave-like plants, yuccas do not have thorny spines or teeth along the edge of their dagger-like leaves.

Beschornerias boast lush green leaves and arching inflorescences of red cylindrical flowers in the spring. In its native habitat it is a woodland plant often found on cliffs above roadsides growing in light to medium shade. Beschorneria septentrionalis‐a tongue-tripping moniker‐produces a flower spike up to three feet tall and requires moist, yet well-drained soils in part shade. A garden colony of these with graceful flower stalks is striking.

Along Mexican roadsides it is common to see scores of salvia plants waving their spikes of blue, purple, or red flowers. While we may be familiar with the culinary sage (Salvia officinalis) from the Mediterranean, the Mexican sages are better adapted to the South’s growing conditions and considerably bolder in color, shape, and texture. Salvias, in general, prefer bright sun and good soil drainage. There are numerous salvias for consideration. For example, there is Salvia greggii, including ‘Big Pink’; Salvia microphylla ‘San Carlos Festival’ with magenta flowers and ‘Cherry Chief’; and the royal blue Salvia mexicana.‘Dulce Nombres’ is a form of the eyelash-leaved sage (Salvia blepharophylla) that was found in Tamaulipas, Mexico, and introduced by Yucca Do Nursery (Hempstead, TX) in 1992; it has red-orange flowers. Many of these salvias are now readily available and relatively inexpensive. For the marginally hardy salvias, Tony Avent, who gardens outside Raleigh, N.C., in Zone 7b, recommends delaying cutting back dead stems of Mexican salvias from the fall to the spring, thereby reducing winter freezing and the potential for damage to the crown.

The skullcap or scutellaria, like salvias, are members of the mint family. Scutellaria suffrutescens is perfect for a rock garden because it forms a small mound, perhaps as high as eight inches and more than twice as wide. It sports pink flowers that are snapdragon-like and does well in a dry, well drained area, taking full sun to light shade.

Tigridia or the Mexican shell flower (Tigridia pavonia) is an iris relative that was grown for its edible bulbs in the gardens of the Aztecs more than 1,000 years ago. It has leaves that are pleated and short-lived flowers that are red to orange and pink, typically spotted or blotched, reminiscent of an ocelot’s spots. They crave rich, well watered soil and partial shade. I have seen them growing in Mexico in the light shade provided by pine and oak forests. Formerly tigridia have been scarce to find in a catalog or nursery, and those that were available in the nursery trade were collected at higher, colder elevations. Now, lower elevation forms of tigridia are becoming accessible and they may adapt more easily to southern gardens. Plants can be easily raised from seed, if available.

Eryngium or sea holly has a deep growing, fleshy taproot like its distant relative the carrot and thus can accept little rainfall. Its spiny evergreen leaves and thistle-like flower heads provide a delicate architecture. Eryngium venustrum from central Mexico has been successfully introduced into gardens from the Carolinas to the Northwest Coast. It has a flat rosette of finely cut foliage, almost doily like. You will want to group several to provide the best effect; but if you do, you’ll need to wear gloves when planting them.

The Mexican barberry (Mahonia gracilis) is an evergreen with shiny leaves that are bright green above and paler below. Unlike many other mahonias, it has no spines. Its creamy yellow flowers appear on an erect raceme in late winter to early spring. It requires part shade and well-drained soil.

The landscape industry in the South has not overlooked the horticultural Mexican connection, including trees such as the evergreen oaks, which expand the palette of available broad-leaf evergreen trees. Monterrey oak (Quercus polymorpha) is a large tree up to 40 to 50 feet with blue-green leaves. Another Mexican oak, Quercus risophylla, is a fast grower with olive-green leaves; it is smaller with a mature height of 30 to 40 feet. These oaks retain their leaves till the spring when they are replaced by a flush of new foliage. The J.C. Raulston Arboretum in Raleigh, N.C., has tested cold hardiness for these and other evergreen Mexican oaks. Both will grow in Zones 7 through 9. An uncommon Mexican form of the dogwood is another tree worth seeking out. Cornus florida ssp. urbiniana has large white bracts that don’t fully open, giving them a handsome lantern-like appearance. Like other dogwoods, it grows in light shade in the understory of larger trees and prefers moist, well-drained rich soil.

If you still have room in your garden for additional Mexican natives, I would recommend an ornamental grass such as Muhlenbergia dumosa, the bamboo muhly. This grass has lacy green foliage on arching cane-like stems that may soar to four feet. It makes a fine companion to strong-textured plants, such as agave and yuccas, as it sways in a gentle breeze. Lastly, don’t overlook the Mexican feather grass (Nassella tenuissima, formerly listed as Stipa tenuissima), which produces a fine fountain of delicate “hair” that floats gracefully in the wind. In its native habitat it grows well in open, dry woods. Plant it in an area where it will contrast nicely by providing an elegant soft edge to large rocks or bold-textured plants.

The autumn is a good time to inventory your garden and consider adding Mexican plants. The woody plants (oaks, dogwood, and mahonia) can be planted in the fall, but you will probably want to wait till the spring for the woody lilies, the salvias, and the skullcap.

[Bobby J. Ward gardens in Raleigh, N.C. He is the author of A Contemplation Upon Plants‐‐Garden Plants in Myth and Literature (Timber Press 1999). He is also the co-editor of A Garden of One’s Own, the writings of Elizabeth Lawrence (UNC Press 1997.]